RARE EARTH ELEMENT (REE) DEPOSIT POTENTIAL IN ARIZONA

Our society is demanding more environmental-friendly technologies like solar panels and wind turbines for electricity, batteries, and electric cars. Other “green” technologies are being developed for water purification, desalination, carbon capture and storage, and light bulbs -- they all require rare earth elements (REE) in their manufacture. Minerals containing REE have been recognized in Arizona for almost a century, but there has been no REE production from Arizona, with the possible exception at the Rare Metals Mine where AZ Bur Mines Bull 180 (1969) states: “several tons of yttrotantalite were obtained”. With the producing, world-class Mountain Pass carbonatite deposit 50 miles west of Arizona, and adjacent New Mexico to the East, with at least 5 REE areas under exploration, it is likely that Arizona also has favorable geologic terrane. Considering the projected increase in demand, and China’s export restrictions on REEs, Arizona REE occurrences and geologic terranes are being examined for their potential. Several types of REE occurrences are found in Arizona, including Proterozoic pegmatites, recent placers, uranium-bearing breccia pipes, and Cretaceous heavy mineral, beach-placer sandstone deposits in the Colorado Plateau. Recent exploration has occurred at the La Paz Property, Rare Metals pegmatite, and White Picacho Peak areas. Although there are no known carbonatites or alkaline igneous rock complexes in Arizona similar to Mountain Pass, CA or New Mexico, areas of high K₂O metasomatism at Picacho Peak and Harcuvar Mountains need examination. Detailed geologic mapping, geochemical analyses, and mineralogy are needed in these areas. Exploration in 2011 near Clara Peak, La Paz Co. in the Harcuvar metamorphic core complex by AusAmerican Mining Corp indicated resources of (unapproved NI43-101) 11.8 million lbs TREE in the lower-plate rocks, primarily in allanite at a grade of 373 ppm; which is about 3x average crustal abundance. REEs are also found in allanite, with an alteration rim of Bastnaesite, at the 70-year ongoing Kingman Feldspar Mine. “Twenty tones of allanite were excavated and sent to an unknown buyer” (AZ Bur Mines Bull 167). Many challenges face mining companies in supplying REE elements. Future development of “green” technologies will be challenging and demand ever more REEs.